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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network240.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
240.0.0.0
Broadcast address
255.255.255.255
First usable
240.0.0.1
Last usable
255.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F0000000 · Integer 4026531840 to 4294967295
Reverse DNS zones
240.in-addr.arpa
241.in-addr.arpa
242.in-addr.arpa
243.in-addr.arpa
244.in-addr.arpa
245.in-addr.arpa
246.in-addr.arpa
247.in-addr.arpa
248.in-addr.arpa
249.in-addr.arpa
250.in-addr.arpa
251.in-addr.arpa
252.in-addr.arpa
253.in-addr.arpa
254.in-addr.arpa
255.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110000.00000000.00000000.00000000240.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network11110000.00000000.00000000.00000000240.0.0.0
Broadcast11111111.11111111.11111111.11111111255.255.255.255
Split into smaller subnets/14
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

240.0.0.0/4 makes 1,024 subnets of /14; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.0.0.0/14240.0.0.1 to 240.3.255.254240.3.255.255262,142
2240.4.0.0/14240.4.0.1 to 240.7.255.254240.7.255.255262,142
3240.8.0.0/14240.8.0.1 to 240.11.255.254240.11.255.255262,142
4240.12.0.0/14240.12.0.1 to 240.15.255.254240.15.255.255262,142
5240.16.0.0/14240.16.0.1 to 240.19.255.254240.19.255.255262,142
6240.20.0.0/14240.20.0.1 to 240.23.255.254240.23.255.255262,142
7240.24.0.0/14240.24.0.1 to 240.27.255.254240.27.255.255262,142
8240.28.0.0/14240.28.0.1 to 240.31.255.254240.31.255.255262,142
9240.32.0.0/14240.32.0.1 to 240.35.255.254240.35.255.255262,142
10240.36.0.0/14240.36.0.1 to 240.39.255.254240.39.255.255262,142
11240.40.0.0/14240.40.0.1 to 240.43.255.254240.43.255.255262,142
12240.44.0.0/14240.44.0.1 to 240.47.255.254240.47.255.255262,142
13240.48.0.0/14240.48.0.1 to 240.51.255.254240.51.255.255262,142
14240.52.0.0/14240.52.0.1 to 240.55.255.254240.55.255.255262,142
15240.56.0.0/14240.56.0.1 to 240.59.255.254240.59.255.255262,142
16240.60.0.0/14240.60.0.1 to 240.63.255.254240.63.255.255262,142
17240.64.0.0/14240.64.0.1 to 240.67.255.254240.67.255.255262,142
18240.68.0.0/14240.68.0.1 to 240.71.255.254240.71.255.255262,142
19240.72.0.0/14240.72.0.1 to 240.75.255.254240.75.255.255262,142
20240.76.0.0/14240.76.0.1 to 240.79.255.254240.79.255.255262,142
21240.80.0.0/14240.80.0.1 to 240.83.255.254240.83.255.255262,142
22240.84.0.0/14240.84.0.1 to 240.87.255.254240.87.255.255262,142
23240.88.0.0/14240.88.0.1 to 240.91.255.254240.91.255.255262,142
24240.92.0.0/14240.92.0.1 to 240.95.255.254240.95.255.255262,142
25240.96.0.0/14240.96.0.1 to 240.99.255.254240.99.255.255262,142
26240.100.0.0/14240.100.0.1 to 240.103.255.254240.103.255.255262,142
27240.104.0.0/14240.104.0.1 to 240.107.255.254240.107.255.255262,142
28240.108.0.0/14240.108.0.1 to 240.111.255.254240.111.255.255262,142
29240.112.0.0/14240.112.0.1 to 240.115.255.254240.115.255.255262,142
30240.116.0.0/14240.116.0.1 to 240.119.255.254240.119.255.255262,142
31240.120.0.0/14240.120.0.1 to 240.123.255.254240.123.255.255262,142
32240.124.0.0/14240.124.0.1 to 240.127.255.254240.127.255.255262,142
33240.128.0.0/14240.128.0.1 to 240.131.255.254240.131.255.255262,142
34240.132.0.0/14240.132.0.1 to 240.135.255.254240.135.255.255262,142
35240.136.0.0/14240.136.0.1 to 240.139.255.254240.139.255.255262,142
36240.140.0.0/14240.140.0.1 to 240.143.255.254240.143.255.255262,142
37240.144.0.0/14240.144.0.1 to 240.147.255.254240.147.255.255262,142
38240.148.0.0/14240.148.0.1 to 240.151.255.254240.151.255.255262,142
39240.152.0.0/14240.152.0.1 to 240.155.255.254240.155.255.255262,142
40240.156.0.0/14240.156.0.1 to 240.159.255.254240.159.255.255262,142
41240.160.0.0/14240.160.0.1 to 240.163.255.254240.163.255.255262,142
42240.164.0.0/14240.164.0.1 to 240.167.255.254240.167.255.255262,142
43240.168.0.0/14240.168.0.1 to 240.171.255.254240.171.255.255262,142
44240.172.0.0/14240.172.0.1 to 240.175.255.254240.175.255.255262,142
45240.176.0.0/14240.176.0.1 to 240.179.255.254240.179.255.255262,142
46240.180.0.0/14240.180.0.1 to 240.183.255.254240.183.255.255262,142
47240.184.0.0/14240.184.0.1 to 240.187.255.254240.187.255.255262,142
48240.188.0.0/14240.188.0.1 to 240.191.255.254240.191.255.255262,142
49240.192.0.0/14240.192.0.1 to 240.195.255.254240.195.255.255262,142
50240.196.0.0/14240.196.0.1 to 240.199.255.254240.199.255.255262,142
51240.200.0.0/14240.200.0.1 to 240.203.255.254240.203.255.255262,142
52240.204.0.0/14240.204.0.1 to 240.207.255.254240.207.255.255262,142
53240.208.0.0/14240.208.0.1 to 240.211.255.254240.211.255.255262,142
54240.212.0.0/14240.212.0.1 to 240.215.255.254240.215.255.255262,142
55240.216.0.0/14240.216.0.1 to 240.219.255.254240.219.255.255262,142
56240.220.0.0/14240.220.0.1 to 240.223.255.254240.223.255.255262,142
57240.224.0.0/14240.224.0.1 to 240.227.255.254240.227.255.255262,142
58240.228.0.0/14240.228.0.1 to 240.231.255.254240.231.255.255262,142
59240.232.0.0/14240.232.0.1 to 240.235.255.254240.235.255.255262,142
60240.236.0.0/14240.236.0.1 to 240.239.255.254240.239.255.255262,142
61240.240.0.0/14240.240.0.1 to 240.243.255.254240.243.255.255262,142
62240.244.0.0/14240.244.0.1 to 240.247.255.254240.247.255.255262,142
63240.248.0.0/14240.248.0.1 to 240.251.255.254240.251.255.255262,142
64240.252.0.0/14240.252.0.1 to 240.255.255.254240.255.255.255262,142
65241.0.0.0/14241.0.0.1 to 241.3.255.254241.3.255.255262,142
66241.4.0.0/14241.4.0.1 to 241.7.255.254241.7.255.255262,142
67241.8.0.0/14241.8.0.1 to 241.11.255.254241.11.255.255262,142
68241.12.0.0/14241.12.0.1 to 241.15.255.254241.15.255.255262,142
69241.16.0.0/14241.16.0.1 to 241.19.255.254241.19.255.255262,142
70241.20.0.0/14241.20.0.1 to 241.23.255.254241.23.255.255262,142
71241.24.0.0/14241.24.0.1 to 241.27.255.254241.27.255.255262,142
72241.28.0.0/14241.28.0.1 to 241.31.255.254241.31.255.255262,142
73241.32.0.0/14241.32.0.1 to 241.35.255.254241.35.255.255262,142
74241.36.0.0/14241.36.0.1 to 241.39.255.254241.39.255.255262,142
75241.40.0.0/14241.40.0.1 to 241.43.255.254241.43.255.255262,142
76241.44.0.0/14241.44.0.1 to 241.47.255.254241.47.255.255262,142
77241.48.0.0/14241.48.0.1 to 241.51.255.254241.51.255.255262,142
78241.52.0.0/14241.52.0.1 to 241.55.255.254241.55.255.255262,142
79241.56.0.0/14241.56.0.1 to 241.59.255.254241.59.255.255262,142
80241.60.0.0/14241.60.0.1 to 241.63.255.254241.63.255.255262,142
81241.64.0.0/14241.64.0.1 to 241.67.255.254241.67.255.255262,142
82241.68.0.0/14241.68.0.1 to 241.71.255.254241.71.255.255262,142
83241.72.0.0/14241.72.0.1 to 241.75.255.254241.75.255.255262,142
84241.76.0.0/14241.76.0.1 to 241.79.255.254241.79.255.255262,142
85241.80.0.0/14241.80.0.1 to 241.83.255.254241.83.255.255262,142
86241.84.0.0/14241.84.0.1 to 241.87.255.254241.87.255.255262,142
87241.88.0.0/14241.88.0.1 to 241.91.255.254241.91.255.255262,142
88241.92.0.0/14241.92.0.1 to 241.95.255.254241.95.255.255262,142
89241.96.0.0/14241.96.0.1 to 241.99.255.254241.99.255.255262,142
90241.100.0.0/14241.100.0.1 to 241.103.255.254241.103.255.255262,142
91241.104.0.0/14241.104.0.1 to 241.107.255.254241.107.255.255262,142
92241.108.0.0/14241.108.0.1 to 241.111.255.254241.111.255.255262,142
93241.112.0.0/14241.112.0.1 to 241.115.255.254241.115.255.255262,142
94241.116.0.0/14241.116.0.1 to 241.119.255.254241.119.255.255262,142
95241.120.0.0/14241.120.0.1 to 241.123.255.254241.123.255.255262,142
96241.124.0.0/14241.124.0.1 to 241.127.255.254241.127.255.255262,142
97241.128.0.0/14241.128.0.1 to 241.131.255.254241.131.255.255262,142
98241.132.0.0/14241.132.0.1 to 241.135.255.254241.135.255.255262,142
99241.136.0.0/14241.136.0.1 to 241.139.255.254241.139.255.255262,142
100241.140.0.0/14241.140.0.1 to 241.143.255.254241.143.255.255262,142
101241.144.0.0/14241.144.0.1 to 241.147.255.254241.147.255.255262,142
102241.148.0.0/14241.148.0.1 to 241.151.255.254241.151.255.255262,142
103241.152.0.0/14241.152.0.1 to 241.155.255.254241.155.255.255262,142
104241.156.0.0/14241.156.0.1 to 241.159.255.254241.159.255.255262,142
105241.160.0.0/14241.160.0.1 to 241.163.255.254241.163.255.255262,142
106241.164.0.0/14241.164.0.1 to 241.167.255.254241.167.255.255262,142
107241.168.0.0/14241.168.0.1 to 241.171.255.254241.171.255.255262,142
108241.172.0.0/14241.172.0.1 to 241.175.255.254241.175.255.255262,142
109241.176.0.0/14241.176.0.1 to 241.179.255.254241.179.255.255262,142
110241.180.0.0/14241.180.0.1 to 241.183.255.254241.183.255.255262,142
111241.184.0.0/14241.184.0.1 to 241.187.255.254241.187.255.255262,142
112241.188.0.0/14241.188.0.1 to 241.191.255.254241.191.255.255262,142
113241.192.0.0/14241.192.0.1 to 241.195.255.254241.195.255.255262,142
114241.196.0.0/14241.196.0.1 to 241.199.255.254241.199.255.255262,142
115241.200.0.0/14241.200.0.1 to 241.203.255.254241.203.255.255262,142
116241.204.0.0/14241.204.0.1 to 241.207.255.254241.207.255.255262,142
117241.208.0.0/14241.208.0.1 to 241.211.255.254241.211.255.255262,142
118241.212.0.0/14241.212.0.1 to 241.215.255.254241.215.255.255262,142
119241.216.0.0/14241.216.0.1 to 241.219.255.254241.219.255.255262,142
120241.220.0.0/14241.220.0.1 to 241.223.255.254241.223.255.255262,142
121241.224.0.0/14241.224.0.1 to 241.227.255.254241.227.255.255262,142
122241.228.0.0/14241.228.0.1 to 241.231.255.254241.231.255.255262,142
123241.232.0.0/14241.232.0.1 to 241.235.255.254241.235.255.255262,142
124241.236.0.0/14241.236.0.1 to 241.239.255.254241.239.255.255262,142
125241.240.0.0/14241.240.0.1 to 241.243.255.254241.243.255.255262,142
126241.244.0.0/14241.244.0.1 to 241.247.255.254241.247.255.255262,142
127241.248.0.0/14241.248.0.1 to 241.251.255.254241.251.255.255262,142
128241.252.0.0/14241.252.0.1 to 241.255.255.254241.255.255.255262,142
129242.0.0.0/14242.0.0.1 to 242.3.255.254242.3.255.255262,142
130242.4.0.0/14242.4.0.1 to 242.7.255.254242.7.255.255262,142
131242.8.0.0/14242.8.0.1 to 242.11.255.254242.11.255.255262,142
132242.12.0.0/14242.12.0.1 to 242.15.255.254242.15.255.255262,142
133242.16.0.0/14242.16.0.1 to 242.19.255.254242.19.255.255262,142
134242.20.0.0/14242.20.0.1 to 242.23.255.254242.23.255.255262,142
135242.24.0.0/14242.24.0.1 to 242.27.255.254242.27.255.255262,142
136242.28.0.0/14242.28.0.1 to 242.31.255.254242.31.255.255262,142
137242.32.0.0/14242.32.0.1 to 242.35.255.254242.35.255.255262,142
138242.36.0.0/14242.36.0.1 to 242.39.255.254242.39.255.255262,142
139242.40.0.0/14242.40.0.1 to 242.43.255.254242.43.255.255262,142
140242.44.0.0/14242.44.0.1 to 242.47.255.254242.47.255.255262,142
141242.48.0.0/14242.48.0.1 to 242.51.255.254242.51.255.255262,142
142242.52.0.0/14242.52.0.1 to 242.55.255.254242.55.255.255262,142
143242.56.0.0/14242.56.0.1 to 242.59.255.254242.59.255.255262,142
144242.60.0.0/14242.60.0.1 to 242.63.255.254242.63.255.255262,142
145242.64.0.0/14242.64.0.1 to 242.67.255.254242.67.255.255262,142
146242.68.0.0/14242.68.0.1 to 242.71.255.254242.71.255.255262,142
147242.72.0.0/14242.72.0.1 to 242.75.255.254242.75.255.255262,142
148242.76.0.0/14242.76.0.1 to 242.79.255.254242.79.255.255262,142
149242.80.0.0/14242.80.0.1 to 242.83.255.254242.83.255.255262,142
150242.84.0.0/14242.84.0.1 to 242.87.255.254242.87.255.255262,142
151242.88.0.0/14242.88.0.1 to 242.91.255.254242.91.255.255262,142
152242.92.0.0/14242.92.0.1 to 242.95.255.254242.95.255.255262,142
153242.96.0.0/14242.96.0.1 to 242.99.255.254242.99.255.255262,142
154242.100.0.0/14242.100.0.1 to 242.103.255.254242.103.255.255262,142
155242.104.0.0/14242.104.0.1 to 242.107.255.254242.107.255.255262,142
156242.108.0.0/14242.108.0.1 to 242.111.255.254242.111.255.255262,142
157242.112.0.0/14242.112.0.1 to 242.115.255.254242.115.255.255262,142
158242.116.0.0/14242.116.0.1 to 242.119.255.254242.119.255.255262,142
159242.120.0.0/14242.120.0.1 to 242.123.255.254242.123.255.255262,142
160242.124.0.0/14242.124.0.1 to 242.127.255.254242.127.255.255262,142
161242.128.0.0/14242.128.0.1 to 242.131.255.254242.131.255.255262,142
162242.132.0.0/14242.132.0.1 to 242.135.255.254242.135.255.255262,142
163242.136.0.0/14242.136.0.1 to 242.139.255.254242.139.255.255262,142
164242.140.0.0/14242.140.0.1 to 242.143.255.254242.143.255.255262,142
165242.144.0.0/14242.144.0.1 to 242.147.255.254242.147.255.255262,142
166242.148.0.0/14242.148.0.1 to 242.151.255.254242.151.255.255262,142
167242.152.0.0/14242.152.0.1 to 242.155.255.254242.155.255.255262,142
168242.156.0.0/14242.156.0.1 to 242.159.255.254242.159.255.255262,142
169242.160.0.0/14242.160.0.1 to 242.163.255.254242.163.255.255262,142
170242.164.0.0/14242.164.0.1 to 242.167.255.254242.167.255.255262,142
171242.168.0.0/14242.168.0.1 to 242.171.255.254242.171.255.255262,142
172242.172.0.0/14242.172.0.1 to 242.175.255.254242.175.255.255262,142
173242.176.0.0/14242.176.0.1 to 242.179.255.254242.179.255.255262,142
174242.180.0.0/14242.180.0.1 to 242.183.255.254242.183.255.255262,142
175242.184.0.0/14242.184.0.1 to 242.187.255.254242.187.255.255262,142
176242.188.0.0/14242.188.0.1 to 242.191.255.254242.191.255.255262,142
177242.192.0.0/14242.192.0.1 to 242.195.255.254242.195.255.255262,142
178242.196.0.0/14242.196.0.1 to 242.199.255.254242.199.255.255262,142
179242.200.0.0/14242.200.0.1 to 242.203.255.254242.203.255.255262,142
180242.204.0.0/14242.204.0.1 to 242.207.255.254242.207.255.255262,142
181242.208.0.0/14242.208.0.1 to 242.211.255.254242.211.255.255262,142
182242.212.0.0/14242.212.0.1 to 242.215.255.254242.215.255.255262,142
183242.216.0.0/14242.216.0.1 to 242.219.255.254242.219.255.255262,142
184242.220.0.0/14242.220.0.1 to 242.223.255.254242.223.255.255262,142
185242.224.0.0/14242.224.0.1 to 242.227.255.254242.227.255.255262,142
186242.228.0.0/14242.228.0.1 to 242.231.255.254242.231.255.255262,142
187242.232.0.0/14242.232.0.1 to 242.235.255.254242.235.255.255262,142
188242.236.0.0/14242.236.0.1 to 242.239.255.254242.239.255.255262,142
189242.240.0.0/14242.240.0.1 to 242.243.255.254242.243.255.255262,142
190242.244.0.0/14242.244.0.1 to 242.247.255.254242.247.255.255262,142
191242.248.0.0/14242.248.0.1 to 242.251.255.254242.251.255.255262,142
192242.252.0.0/14242.252.0.1 to 242.255.255.254242.255.255.255262,142
193243.0.0.0/14243.0.0.1 to 243.3.255.254243.3.255.255262,142
194243.4.0.0/14243.4.0.1 to 243.7.255.254243.7.255.255262,142
195243.8.0.0/14243.8.0.1 to 243.11.255.254243.11.255.255262,142
196243.12.0.0/14243.12.0.1 to 243.15.255.254243.15.255.255262,142
197243.16.0.0/14243.16.0.1 to 243.19.255.254243.19.255.255262,142
198243.20.0.0/14243.20.0.1 to 243.23.255.254243.23.255.255262,142
199243.24.0.0/14243.24.0.1 to 243.27.255.254243.27.255.255262,142
200243.28.0.0/14243.28.0.1 to 243.31.255.254243.31.255.255262,142
201243.32.0.0/14243.32.0.1 to 243.35.255.254243.35.255.255262,142
202243.36.0.0/14243.36.0.1 to 243.39.255.254243.39.255.255262,142
203243.40.0.0/14243.40.0.1 to 243.43.255.254243.43.255.255262,142
204243.44.0.0/14243.44.0.1 to 243.47.255.254243.47.255.255262,142
205243.48.0.0/14243.48.0.1 to 243.51.255.254243.51.255.255262,142
206243.52.0.0/14243.52.0.1 to 243.55.255.254243.55.255.255262,142
207243.56.0.0/14243.56.0.1 to 243.59.255.254243.59.255.255262,142
208243.60.0.0/14243.60.0.1 to 243.63.255.254243.63.255.255262,142
209243.64.0.0/14243.64.0.1 to 243.67.255.254243.67.255.255262,142
210243.68.0.0/14243.68.0.1 to 243.71.255.254243.71.255.255262,142
211243.72.0.0/14243.72.0.1 to 243.75.255.254243.75.255.255262,142
212243.76.0.0/14243.76.0.1 to 243.79.255.254243.79.255.255262,142
213243.80.0.0/14243.80.0.1 to 243.83.255.254243.83.255.255262,142
214243.84.0.0/14243.84.0.1 to 243.87.255.254243.87.255.255262,142
215243.88.0.0/14243.88.0.1 to 243.91.255.254243.91.255.255262,142
216243.92.0.0/14243.92.0.1 to 243.95.255.254243.95.255.255262,142
217243.96.0.0/14243.96.0.1 to 243.99.255.254243.99.255.255262,142
218243.100.0.0/14243.100.0.1 to 243.103.255.254243.103.255.255262,142
219243.104.0.0/14243.104.0.1 to 243.107.255.254243.107.255.255262,142
220243.108.0.0/14243.108.0.1 to 243.111.255.254243.111.255.255262,142
221243.112.0.0/14243.112.0.1 to 243.115.255.254243.115.255.255262,142
222243.116.0.0/14243.116.0.1 to 243.119.255.254243.119.255.255262,142
223243.120.0.0/14243.120.0.1 to 243.123.255.254243.123.255.255262,142
224243.124.0.0/14243.124.0.1 to 243.127.255.254243.127.255.255262,142
225243.128.0.0/14243.128.0.1 to 243.131.255.254243.131.255.255262,142
226243.132.0.0/14243.132.0.1 to 243.135.255.254243.135.255.255262,142
227243.136.0.0/14243.136.0.1 to 243.139.255.254243.139.255.255262,142
228243.140.0.0/14243.140.0.1 to 243.143.255.254243.143.255.255262,142
229243.144.0.0/14243.144.0.1 to 243.147.255.254243.147.255.255262,142
230243.148.0.0/14243.148.0.1 to 243.151.255.254243.151.255.255262,142
231243.152.0.0/14243.152.0.1 to 243.155.255.254243.155.255.255262,142
232243.156.0.0/14243.156.0.1 to 243.159.255.254243.159.255.255262,142
233243.160.0.0/14243.160.0.1 to 243.163.255.254243.163.255.255262,142
234243.164.0.0/14243.164.0.1 to 243.167.255.254243.167.255.255262,142
235243.168.0.0/14243.168.0.1 to 243.171.255.254243.171.255.255262,142
236243.172.0.0/14243.172.0.1 to 243.175.255.254243.175.255.255262,142
237243.176.0.0/14243.176.0.1 to 243.179.255.254243.179.255.255262,142
238243.180.0.0/14243.180.0.1 to 243.183.255.254243.183.255.255262,142
239243.184.0.0/14243.184.0.1 to 243.187.255.254243.187.255.255262,142
240243.188.0.0/14243.188.0.1 to 243.191.255.254243.191.255.255262,142
241243.192.0.0/14243.192.0.1 to 243.195.255.254243.195.255.255262,142
242243.196.0.0/14243.196.0.1 to 243.199.255.254243.199.255.255262,142
243243.200.0.0/14243.200.0.1 to 243.203.255.254243.203.255.255262,142
244243.204.0.0/14243.204.0.1 to 243.207.255.254243.207.255.255262,142
245243.208.0.0/14243.208.0.1 to 243.211.255.254243.211.255.255262,142
246243.212.0.0/14243.212.0.1 to 243.215.255.254243.215.255.255262,142
247243.216.0.0/14243.216.0.1 to 243.219.255.254243.219.255.255262,142
248243.220.0.0/14243.220.0.1 to 243.223.255.254243.223.255.255262,142
249243.224.0.0/14243.224.0.1 to 243.227.255.254243.227.255.255262,142
250243.228.0.0/14243.228.0.1 to 243.231.255.254243.231.255.255262,142
251243.232.0.0/14243.232.0.1 to 243.235.255.254243.235.255.255262,142
252243.236.0.0/14243.236.0.1 to 243.239.255.254243.239.255.255262,142
253243.240.0.0/14243.240.0.1 to 243.243.255.254243.243.255.255262,142
254243.244.0.0/14243.244.0.1 to 243.247.255.254243.247.255.255262,142
255243.248.0.0/14243.248.0.1 to 243.251.255.254243.251.255.255262,142
256243.252.0.0/14243.252.0.1 to 243.255.255.254243.255.255.255262,142

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.